One of the major problems encountered with rotary engines is in providing effective sealing between the rotary piston and the housing for insuring efficient pressure isolation of the several pressure chambers relative to each other during operation of the engine. The sealing elements used for this purpose are usually in the form of elongated strips radially slidably disposed in receiving slots formed either in apexes of the housing or the apexes of the rotary piston, depending upon the design of the engine, said strips having a sealing edge making sealing contact with either the peripheral surface of the piston or the inner contour curved surface of the housing, as the case may be, the other edge of said sealing strip usually having acting thereagainst some form of spring means for urging the sealing edge of the sealing strip into sealing contact with the surface it rides against. Since the pressure in the chamber being pressurized acts against the sealing edge of the sealing strip and, therefore, in opposing relation to the force exerted by the spring means, the sealing effect, as well as the efficiency of the engine, is undesirably reduced.
One of the presently known solutions to the problem above set forth provides means for communicating pressure from the chamber being pressurized to a space behind the sealing strip, which thus not only compensates for the pressure acting on the sealing edge, but also assists the spring means in pressing the sealing strip into better sealing engagement with the surface contacted. In order to communicate pressure to the space behind the sealing strip, various bore and valve arrangements have been provided either in the housing or piston, but these arrangements have been found to be too costly or do not necessarily provide trouble-free operation.